Electrical conductor



K. L. ORSER ELECTRICAL CONDUCTOR Dec. 14, 1948.

Filed Aug. 1. 1944.

KEITH ,L. OR53F Patented Dec. 14, 1948 ELECTRICAL CONDUCTOR Keith L. Orser, Auburn, N. Y., assignor to Columbian Rope Company, Auburn. N. Y., a corporation of New York Application August 1, 1944, Serial No. 547,590

2 Claims. (01. 174-69) This invention relates to electrical conductors and particularly to a conductor for use in load sustaining structures such as ropes.

The primary object of the invention is to provide an electricalconductor unit, such as an insulated wire for telephone circuits which can be used in combination with load sustaining structures or ropes that are elongated when the load is imposed thereon.

Another object is to provide a load sustaining structure or rope which has a relatively high elongation and recovery factor with a protected, insulated electrical conductor or telephone line wire which will accommodate itself to the stretching and recovery of said structure.

A still further object is to provide an electrical conductor unit especially adapted for incorporation in a load carrying rope. said unit being a counterpart of any of the individual yarns of which the rope is made, so far as concerns the elongation factor inherent in said yarns.

For instance, in the use oi! glider planes towed by powered planes, ropes having a high elongation and recovery'iactor are,preierably used as tow lines in order to absorb sudden shocks or strains imposed thereon during the take-oil" as well as under various other circumstances. It is also usually the practice to provide for interphone communication between the occupants of the connected power plane and glider planes but considerable dimculty has been experienced in maintaining the line connections between the telephone instruments due to the stretching of the tow lines and the resulting variances in the distance between connected planes. Heretoifore, the telephone wires between two connected planes have been "draped or festooned along the tow line and taped or tied to the tow line at longitudinally spaced points so that the slack in the wires between each two points of attachment could compensate for the stretching of the tow line. Rope made 01' nylon has generally been adopted for use as glider tow lines and as rope of this character has a very high elongation factor the loops formed in the testooned wire are quite large and render it diflicult to properly maintain the intercommunication system by reason of the fact that these suspended loops are irequently damaged, especially in the take-ofl oi thepianu and when the tow lines are dropped.

2 One particular form 01 damage to the communication lines is the destruction of their insulation covering which is quickly worn off by abrasion of the iestooned loops. Specifically, therefore, the invention seeks to provide a glider plane tow line provided with insulated telephone line wires that will fully compensate for elongation of the tow line and which. at the same time, will be fully protected against abrasion or other damage under all conditions of usage.

In the accompanying drawing Figure 1 illustrates a short section of a stranded rope having a plurality of telephone line wires therein;

Fig. 2 is an enlarged view of one of the line wires; and

Fig. 3 is a detail view illustrating the preferred manner of splicing the present rope when made of nylon and used for towing glider planes.

In the embodiment of the invention each conductor unit or element is embedded in a strand of the rope, the rope being illustrated as consisting of three strands l0 although the invention is not limited to the use of any particular number of strands. In accordance with standard rope manufacturing practices each strand is made of a plurality of spun yarns twisted. to-

. gether in strand formation and, for purposes of this disclosure, the yarns will be assumed to be made oi. a multiplicity of nylon" threads or elements spun or twisted into yarns. Also, in accordance with the usual practices of rope manufacture, the direction in which the nylon is twisted in spinning the yarns and the directions in which the yarns are twisted into strands and the strands into ropes are so arranged as to produce a stable rope structure. However, due to the high degree of stretchability or elongation of the nylon and the ability of the rope to elongate under tension by reason of the twist in its structural elements, it has been impossible to satisfactorily combine an electrical conductor or telephone line wire with such a rope, as previously pointed out.

To overcome all the difllculties outlined above, the present invention contemplates an electrical conductor unit which possesses substantially the same elongation and recovery factory as is possessed by the yarns of the rope in conjunction with which it is to be used. In its preferred form,

which is illustrated in Fig. 2, this conductor unit comprises a core ll around which the conductor wire I! is wrapped and an elastic covering l3 of non-conductive material for insulating the wire. Rubber insulation or other non-conductive material having the necessary elasticity can be used. The core III is preferably made of a multiplicity of filaments of the same material as is used in the rope yarns, in this instance nylon, and these filaments are also preferably spun or twisted into a yarn which constitutes said core. This so-called core has the same degree of twist as the yarn composing the strands l0. Usually, the conductor element I2 is composed of a plurality of small wires which are disposed parallel to each other spirally of the core II, asshown. By reason of the parallel, spiral disposition of the several ends of the conductor wire i2 and the spiral arrangement of the nylon filaments of core H, the conductor unit as a whole, including the elastic insulation covering l3, has an elongation and recovery factor substantially corresponding to that of the individual yarns and of the rope itself. In accordance with the present invention, this conductor unit is preferably associated with the rope by being incorporated in the strand at a point where it will not be exposed at the surface of the rope. Any point within the interior of the strand will prove entirely satisfactory although the nearer the center of the strands the conductor unit is located, the less the unit will have to elongate and straighten out when the rope is placed under tension and the strands and yarns elongate and tend to untwist. In some instances the conductor unit can be located at the geometrical center of the strand, thus constituting a core or center for the strand. In other instances where no one yarn is located at the geometrical center, the conductor is run into the strand as one of the core yarns, all of which, including the con ductor, are enclosed within and protected by the outer or cover yarns of the strand. This is en tirely feasable because. as pointed out the conductor unit has an elongation or stretching factor equal to the normal yarns of which the strand is formed and hence the conductor can be substituted, so to speak, for any one of the yarns, However, as indicated, it should be located beneath the surface of the strand so as to insure against it bein damaged by abrasion by surfaces against which the rope may contact. This renders the present rope construction highly adaptable for use as tow-lines for glider planes as there is little, if any, danger of the conductor wires breaking or of the unit as a whole being damaged so that inter-telephonic communication can be maintained between planes under all conditions with maximum efilciency.

Conductor units having a nylon core made of .050" diameter with five turns per inch of sixteen #34 wires have been found to give very satisfactory results under actual flying conditions but it will be appreciatedthatthe number of turns. per unit of length, used in wrapping the wire on the core may be varied as the elongation permitted the conductor wires will bear a more or less predetermined relationship to the elongation factor of the core and rope proper. In other words, if the rope strands and core ll of the conductor are made of a material having an elongation factor different from that of nylon, the number of turns, per inch, given the conductor wires may be varied accordingly, a smaller number of turns being required as the elongation factor decreases and a larger number of turns being used as the elongation factor increases. While it is preferred to make core ll of the conductor unit and strands ill of the rope of one and the same material, such practice need not be adhered to strictly so long as the materials used in these two elements possess substantially the same elongation factors. It will also be understood that the number of wires or the size of the wires used for conductor I2 may also be varied. Depending upon the electrical conductivity desired for conductor II, the number of wires can be varied with their size remaining constant or their number can remain constant and their size varied, or both.

The present rope made of nylon, with the conductor unit incorporated therein as described, has been used in numerous glider flights and for pur poses of connecting up the conductor wires in these actual flights, the construction illustrated in Fig. 3 has proven highly satisfactory. The end of the tow line is run through a metallic U -shaped thimble H with a tape wrapping it interposed between the rope and thimble to protect against abrasion. The rope is then spliced by inserting or "tucking each strand of the free end of the rope between strands of the rope at a point in advance of the thimble. Four of these tucks are made with eachstrand containing the conductor after which one-half of the yarns in the remaining free ends of the strands are cut off. The conductor wire is then withheld at the exterior of the rope to form leads and the remaining half-portions oi' the strands, indicated at ill, are each inserted between the full strands twice to form what are termed two half-tucks in each one. The unused portions of the half-strands are then cut off with the result that the spliced portion tapers more or less until its diameter substantially corresponds to the normal diameter of the rope.

A more or less detailed description of nylon tow line for glider planes has been adopted for pur poses of disclosing the present invention as the latter has been developed in connection with the production of nylon rope but it will be understood that the invention is not limited to this particular type of rope or tow line except as expressly set forth in the appended claims.

What I claim is:

1. A stranded rope structure, each strand being composed of a plurality of spirally arranged load carrying elements of twisted filaments of stretchable non-metallic material, certain of said strands having an electrical conductor element embedded therein having a core constituted of twisted filaments forming one of said load carrying elements, electrical conducting wire arranged spirally around said core and an elastic non-conductive covering encasing said wire, the twisted filaments forming the core of said conductor elements having elongation and recovery characteristics substantially corresponding to the elongation and recovery characteristics of the twisted filaments forming other load carrying elements of the strands in which said conductor elements are embedded.

2. A stranded rope structure, each strand being composed of a plurality of spirally arranged load carrying elements of twisted nylon filaments, cer tain of said strands having an electrical conductor element embedded therein having a core constituted of twisted nylon filaments forming one of said load carrying elements, electrical conducting wire arranged spirally around said core and an elastic non-conductive covering encasing said wire, the twisted nylon filaments forming the core of said conductor elements having elongationand recovery characteristics substantially correspending to the elongation and recovery characteristics of the twisted nylon filaments forming other load carrying elements 01' the strands in which said conductor elements are embedded.

KEITH L. ORSER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Verriil Oct. 28, 1890 Number Number Number 

